1. Field of the Invention
The present invention relates to a test tube holder used in conveying a test tube containing a specimen such as blood.
2. Description of the Related Art
A test tube containing a specimen such as blood is a transparent glass or plastic tube fitted with a rubber or plastic cap on its top opening. In order to convey the specimen in the test tube to each of processing sections for aliquoting or dispensing, the test tube is held vertically in a test tube holder that is guided along a conveying path.
To this end, the test tube holder is configured to hold and convey any of various test tubes having different lengths and diameters in a stable vertical position. Specifically, an engagement portion formed of an annular groove, which is engageable with a guide rail of a conveying system, is disposed on the outer peripheral surface of a proximal end portion of a base that constitutes a holder body. Further, a cylindrical hollow portion that accommodates a test tube is formed to a predetermined depth along the axis of the base so as to extend from its distal end toward proximal end. In some known test tube holders, moreover, a test tube adapter portion that can alternatively hold test tubes having different outside diameters is disposed in a cylindrical hollow portion of a holder body (e.g., Jpn. Pat. Appln. KOKAI Publications Nos. 2003-211006 and 2006-281018).
In the test tube holder described in Jpn. Pat. Appln. KOKAI Publication No. 2003-211006, however, leaf springs disposed in the cylindrical hollow portion of the holder body include contact portions, which are configured to contact the outer peripheral surface of a test tube to be held. Further, this test tube holder is provided with a single O-ring, which binds the leaf springs so as to surround them in order to press the contact portions of the adapter portion against the outer peripheral surface of the test tube at a given pressure.
Thus, the leaf springs have complex structures and their elasticity is compensated for by the single O-ring. Consequently, poor assemblability increases cost, and the O-ring involves troublesome maintenance if it is damaged.
In the test tube holder described in Jpn. Pat. Appln. KOKAI Publication No. 2006-281018, moreover, a holder unit is formed of a holder spring, which includes a plurality of wires of a predetermined length arranged in a circular ring. The distal end portion of the holder spring projects upward from the holder body to form a test tube holder portion, which is elastic radially relative to the cylindrical hollow portion.
Thus, the test tube cannot be stably held vertically, and the structure of the holder unit is so complex that its assemblability is poor, which increases its cost.